The present invention relates to apparatus for purifying exhaust gases of internal combustion engines of automotive vehicles.
There are three kinds of catalytic converters, namely a reducing catalytic converter for elimination of nitrogen oxides, an oxidizing catalytic converter for elimination of carbon monoxide and hydrocarbons, and three-way converters for reacting the three noxious elements at the same time. The converters comprise a catalyst bed comprising a pellet type catalyst element or monolithic or honeycomb catalyst element. The monolithic catalyst element has a series of longitudinally oriented passages, so that exhaust gases may flow smoothly through the catalyst element. However, there is a problem that reaction may not be sufficiently carried out to reduce each noxious conponent to the required level because of short residence time of the gas flow.
Further, in the conventional catalytic converter the axial line of the inlet port is arranged to make a right angle with the front plane of the catalyst element at the central portion thereof. Although the inlet port communicates the catalyst element through the cone-shaped guide duct, the exhaust gas flow cannot sufficiently diffuse up to the entire front plane of the catalyst element and hence has a tendency to collect in the central portion of the front plane. Consequently, the central portion is heated at a high temperature resulting early in damage to the portion.
Therefore, it is the object of the present invention to provide a catalytic converter which may uniformly distribute the exhaust gases to the monolithic catalyst element, thereby achieving maximum reaction efficiency.
According to the present invention, a diffuser means is provided in the inlet chamber of the catalytic converter for distributing the exhaust gases uniformly to the monolithic catalyst element.